Systematics and diversity of terrestrial molluscs

Terrestrial molluscs of East Africa

Staff: Ben Rowson, Jennifer Gallichan, Peter Tattersfield

The sharp boundary between cultivation and a forest reserve in the Ukaguru Mountains, Tanzania.

Scientific study of Africa’s biodiversity bears a strong colonial legacy. Historical collections made mainly by European explorer-naturalists, from before the colonial period until the mid-20th century, are the primary resource for most systematic and identification work subsequently carried out on African invertebrates. The resulting literature is scattered and many works are rare or inaccessible, especially in Africa itself. This project aims to use the Museum’s unique collections, library and expertise to further the study of East African terrestrial molluscs (land-snails and slugs) and make the findings accessible. This requires exploration and primary research as well as the synthesis of existing works, in collaboration with colleagues in Africa and elsewhere. Since the 1990s, Museum staff have been involved with biodiversity surveys, capacity building, and taxonomic work in Kenya, Tanzania and Uganda.

Land-snails in East Africa

Limicolaria from Kampala, Uganda; a smaller relative of the Giant African Snail.

Despite their importance in ecosystems and agriculture, land-snails in tropical East Africa (Kenya, Tanzania and Uganda) remain poorly known. The fauna is quite unlike that found elsewhere in the tropics. The complex geological history of the region has contributed to the evolution of hundreds of endemic species and many endemic genera, some widespread and others restricted to tiny areas. Among these are the famous “Giant African Land Snails” (Lissachatina spp.), the carnivorous hunter snails (Streptaxidae), Afroalpine species with Palearctic affinities, and a host of leaf-litter-dwelling microsnails.

The majority of taxa live only in forest habitats which face a number of threats, yet have historically received less attention than East Africa’s savannas and lakes. The forest centres of endemism under study include the Eastern Arc Mountains, the Albertine Rift, the volcanic highlands of Kenya, and the Indian Ocean coast and onshore islands. In such areas, relict species millions of years old coexist with those arising from Pleistocene climate change, resulting in one of the world’s biodiversity hotspots.

History of the project

The Museum’s existing collections formed the primary resource for the project. The Melvill-Tomlin collection (accessioned 1955) contains much type and other material from major workers on the African fauna, including M. W. K. Connolly, H. B. Preston and E. A. Smith, as well as Melvill and Tomlin themselves who both described African taxa. The Tom Pain collection (accessioned 1981) includes many further African species and is particularly rich in Achatinidae cited in Pain’s own work. Visiting specialists including Al Mead and Bernard Verdcourt, have reviewed and cited parts of the collection. Verdcourt, the twentieth century’s leading authority on East African land-snails, recently donated much of his malacological library and archives which provide an unparalleled resource for further study.

Since the early 1990s we have conducted biodiversity surveys of land-snails in forest habitats in Kenya, Tanzania and Uganda. The results to date (see Publications) have increased our understanding of the community ecology of land-snails in native forest and plantations, and distribution patterns on the scale of individual mountains. Faunistic work based on these collections has tackled these patterns on a larger scale, and descriptions of new species have hinted at what remains to be discovered. Systematic research addresses the evolution and biogeography of the fauna and its relationships to others around the world. Capacity building has involved field, curatorial and research training and led to the establishment or augmentation of collections in the National Museums of Tanzania, National Museums of Kenya, and at Makarere University, Uganda. Our collections and data resulting from the surveys are the basis for our ongoing research. We are designing an illustrated guide to the land-snails of Kenya as a taxonomic tool.

The current research programme was developed in the 1990s by former staff member Mary B. Seddon and Research Associate Peter Tattersfield. Current staff members Ben Rowson and Jennifer Gallichan joined the project in 2003 and 2006. Our colleagues Charles Lange (National Museums of Kenya) and Christine Ngereza (National Museums of Tanzania) have been involved since 1996. Different aspects of the project have been supported at different times by DEFRA’s Darwin Initiative programme, Fauna and Flora International, the British Ecological Society, the People’s Trust for Endangered Species, the Linnean Society of London, UNITAS Malacologica, the EU’s SYNTHESYS scheme and other bodies.

Evolution of tropical carnivorous snails (Streptaxidae)

Staff: Ben Rowson

Live Streptaxidae from East Africa. Live-collected specimens are necessary for anatomical and molecular work.

Shell and anatomy of a Primigulella from Tanzania.

Carnivorous land-snails of the family Streptaxidae (sometimes called “hunter snails”) are the most diverse group in the Afrotropical region. They also occur in South America, Asia and the islands of the Indian Ocean. This project aims to clarify the origin, biogeography and great variety of form of streptaxids using morphological and molecular systematic approaches. Some of this research formed a PhD awarded by Cardiff University in 2010.

The British terrestrial mollusc fauna

Some of the British land-snails and slug species, illustrated by various methods.

The Shelled Slug Testacella maugei, from an allotment in Wales. The fingernail-like shell is visible near the tail.

Carnivorous slugs in Britain

Staff: Ben Rowson and Bill Symondson (Cardiff University)

Gardeners are sometimes surprised to learn that there are a number of carnivorous slug species in the British Isles. The Shelled Slugs (Testacella spp.) are curious-looking, subterranean animals that feed almost entirely on live earthworms. They are seldom seen and are difficult to find. The number of species in Europe is unclear, as is their native or introduced status in Britain, and there are many gaps in our knowledge of their behaviour.

In 2007 we were surprised to discover an additional carnivorous slug in South Wales. Despite several similarities to Shelled Slugs, the so-called Ghost Slug (Selenochlamys ysbryda) is quite unrelated and is probably a recent accidental introduction from the western Caucasus region. Thanks to an enthusiastic public response we have been tracking sightings of the Ghost Slug and have acquired enough material of the various Shelled Slugs to begin taxonomic research on the family.

Our Rhagor web-site has more information on how to contribute, including an ID guide to these species and how to distinguish them from other slugs.

Past projects in this research area

Eva Sharland carried out a Countryside Council for Wales-funded PhD project (completed 2001) on the ecology of two endangered land-snails (Vertigo angustior and V. geyeri ) in the British Isles.

Taxonomic tools

Illustrated guide to Kenyan land-snails

Staff: Ben Rowson, Jen Gallichan

Four of the approximately 80 Kenyan species of Gulella: work in progress on the guide to snails.

An important long-term goal of the East African project has been to produce an illustrated guide to the land-snails of Kenya. We now have photographs of nearly all East African taxa, in many cases from the type specimens in our collection or those of other museums, and are currently compiling records and collating the species accounts.

Past projects in this research area

Terrestrial molluscs of Madeira

Molluscs from the Madeiran Islands are well-represented in the collections in Cardiff. The historical collections include type material from Lowe, Watson and Wollaston. Since 1986, the Museum has acquired modern material with good locality data from the Holyoak-Seddon collection and from Professor Robert Cameron. This material has been used in research publications, and is figured in the illustrated guide (Seddon, M. B. 2008. The Landsnails of Madeira: an illustrated compendium of the landsnails and slugs of the Madeiran archipelago. Biotir 2, National Museum of Wales). Click here for an order form.

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